This invention relates to magnetic disk drives, and more particularly, to a disk drive having a removable cartridge.
Magnetic disk drives which write and read digital data from flexible magnetic disks have been extensively used. These are frequently referred to as "floppy" disks and "floppy disk drives." These drives have been extensively used for small, so-called microcomputer systems, for word-processing applications and the like. The flexible disk cartridge includes a relatively thin, flexible jacket which is inserted into the floppy disk drive. The disk drive clamps the flexible disk onto a motor shaft which rotates the disk which is contacted by a read/write head. This cartridge exposes certain areas of the disk recording surface to dust contamination, liquid spillage, fingerprints, and scratching. Also, the flexible jacket allows the possibility of mechanical damage to the entire disk.
Floppy disk drives have the great advantage of ease of insertion and changing the magnetic disk cartridge so that the operator can select the disk cartridge upon which the drive is to operate. However, present day floppy disk drives are not capable of operating with the precision, high speed data capacity and reliability which is present in the rigid disk drives.
Rigid disk drives, such as the IBM 3350, usually have a fixed rigid magnetic media. The magnetic heads do not contact the magnetic surface, but ride on a thin film of air. Because of this, and other features, these disk drives are capable of extremely precise and high speed operation. This type of disk drive is commonly referred to as a "Winchester" drive.
Recently, "Bernoulli" disk drives having performance characteristics similar to that of Winchester drives, but with removable cartridges, have been developed. A flexible magnetic disk is enclosed in a rigid box which is normally completely closed. As the cartridge is inserted into the drive, a slider on the cartridge is moved to an open position so that the flexible disk can be engaged by the hub of a motor which rotates the disk in a read/write relationship with a magnetic head. Access for a rotary actuator is through this same opening from which the slider is moved. The disk is rotated in proximity to a Bernoulli plate which stabilizes the disk.
U.S. Pat. No. 4,400,748-Bauck, et al and related patents to the common assignee show such drives using Bernoulli stabilized flexible disks. U.S. Pat. No. 4,901,173-Jones, et al and related patents to a common assignee, show improvements which relate to so-called "half height" drives. The disclosure of these patents is incorporated herein by reference.
Packaging and volume constraints of removable cartridge disk drives place them at a disadvantage as compared to fixed "Winchester" disk drives with in-hub motors. This is because these types of Winchester drives share the vertical space required for the motor with the vertical space required for the disks. Because no vertical space is needed for disengagement of the motor and disks, a large part of the entire height of the drive can be filled with disks, since the in-hub motor co-exists in this vertical space. The net result is more data capacity.
In a removable cartridge disk drive, the motor and disks typically do not share the same vertical space. To share this space the disks and cartridge would have to pass through the motor when inserting the cartridge, or the motor or cartridge would have to be translated vertically to engage and disengage the motor and disks. The disadvantage of this vertical translation is that it sweeps out vertical height that in the operating state cannot be utilized for disks like the above-mentioned fixed Winchester disk drive.